BIOLOGICAL BASIS OF OBSESSIVE-COMPULSIVE DISORDER

Obsessive-compulsive disorder (OCD) is a multidimensional and etiologi cally heterogenous condition. In this paper, we review genetic, neuroa natomical/neuroimaging and neurochemical studies which clearly indicat e the existence of a biological substrate for this pathology. Although results are not entirely consistent, the majority of genetic studies suggest that there is a familial determinant in OCD. On the other hand , recent structural and functional (CT, MRI, SPECT, PET, fMR) neuroima ging investigations have pointed to hyperactivity of prefrontal-striat al-thalamic circuitry in patients with OCD. Likewise, it is well estab lished that drugs that produce a potent blockade of serotonin (5-HT) r euptake (SSRIs) have efficacy in the treatment of OCD, suggesting that serotonergic system could be implicated in this disorder. This ''5-HT hypothesis'' is also supported by numerous neurochemical/neuroendocri ne studies. Finally, several reports demonstrating a dysfunction of ey e movements in TOC are described.